Resolving taxonomic and nomenclatural problems in the genus Caligus O. F. Müller, 1785 (Copepoda: Caligidae) Author Boxshall, Geoffrey A. Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW 7 5 BD, UK Author Bernot, James P. Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington DC, 20560, USA Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA text Zootaxa 2023 2023-10-30 5360 4 545 567 https://www.mapress.com/zt/article/download/zootaxa.5360.4.5/52133 journal article 10.11646/zootaxa.5360.4.5 1175-5326 10084656 EA1BE6F9-88E2-4357-895E-8ED415206592 Caligus clavatus Kirtisinghe, 1964 and Caligus sphyraeni Pillai, 1963 In 1963 Pillai described C. sphyraeni from Sphyraena acutipinnis Day, 1876 and S. Jello Cuvier, 1829 caught In Indian waters off Trivandrum ( Pillai, 1963 ) and the following year Kirtisinghe (1964) described C. clavatus from S. obtusata Cuvier, 1829 caught in waters off Colombo, Sri Lanka . Pillai (1967 ; 1985 ) recognised that these Caligus species were synonymous but opted to use C. clavatus Kirtisinghe, 1964 for this taxon because of the similarity between his original name and the name of an unrelated congeneric species, Caligus sphyraenae Nuñes-Ruivo & Fourmanoir, 1956 . This action was followed by Ho & Lin (2004) but both C. sphyraeni and C. clavatus have continued to be listed as valid in the World of Copepods website ( Walter & Boxshall, 2023 ). Caligus sphyraeni Pillai, 1963 is not strictly a homonym of Nuñes-Ruivo & Fourmanoir’s (1956) species and there is no necessity to suppress Pillai’s name, which has priority. We therefore treat Caligus clavatus Kirtisinghe, 1964 as a junior subjective synonym of C. sphyraeni Pillai, 1963 . We note that Caligus sphyraenae Nuñes-Ruivo & Fourmanoir, 1956 was considered to be a junior synonym of C. infestans Heller, 1865 by Cressey & Cressey (1980) and Pillai (1985) .